“The Man in the Yellow Suit” is episode nine of season one of The Flash and the mid-season finale.
It’s the Christmas season and a man is hanging up lights. He’s just finished when two blurs speed past him and all the lights go out. Barry is running, not in the Flash uniform, in pursuit of a man in a yellow suit and glowing red eyes. The man Barry saw kill his mother. Then it goes back a day.
Joe and Barry are decorating; well, Joe is, Barry is sitting on the couch. Barry says it’s going to take forever decorating at this speed, so does some decorating at superspeed. Iris comes in with some eggnog and Joe gets a call from the DA and has to leave. Iris wants her and Barry to open their presents to each other, in advance of Christmas, which seems to be something they do. Barry has got a replica of Iris’ mother’s wedding ring on a chain; she lost the real one on a school trip years earlier. She has got him a microscope. The Eddie arrives.
Later, at S.T.A.R. Labs, Barry has brought presents and eggnog for the others, in thanks for what they’ve done for him in the past year. Dr. Wells doesn’t seem entirely happy; according to Caitlin, Christmas used to be his favourite time of the year but the accident happened just prior to it, which has taken the shine off.
Eddie is talking to Iris at the coffee shop. He’s suggesting that Barry might really like her – he gave her a ring after all – but Iris still thinks that Barry is just her best friend. Eddie then gives Iris a ring box, but inside is a key, not a ring. They’re been dating for a year and Eddie thinks they should move in together.
Caitlin is in a garage after looking for a present for Dr. Wells, when she sees a man reflected in the car window. She looks around and there is a man stood in the shadows. At the end of the previous episode, “Flash vs. Arrow”, a man had burst into flames, and this man does the same. The flames allow Caitlin to recognise the man as her fiancée, Ronnie, who was revealed in “Things You Can’t Outrun” to have died during the accident. Only it seems he actually became a meta-human.
At Mercury Labs, in the Superluminal Development area, one of the scientists is leaving and talking to a couple of security guards when an alarm goes off. The guards draw their weapons and tell the man to get to safety, which he does. Then a blur comes in and takes out the two guards before standing in front of the door the scientist is on the other side of. It’s the man in the yellow suit.
At the crime scene the next day, Barry tells Joe that the two guards were killed by a high speed collision, but whatever it was had to be travelling really fast. The scientist had mentioned the blur and Eddie, who is now heading a task force to track down the Flash after Barry got affected by another meta-human and attacked Eddie, assumes it was the Flash. Only when the scientist says it was a man in a yellow suit, Barry realises that it’s the man who killed his mother, and that he’s back.
Barry tells Joe and says he needs to get his files. Joe states that he knew that the man in the yellow suit had been back for several weeks at least. Because, in “The Flash is Born”, he turned up at Joe’s, stole all of Barry’s files and the evidence, and threatened to kill Iris.
Mercury Labs are supposedly working on the technology of the future. Which Wells says is tachyons. Which travel faster than light. Which would make the Flash look positively slow. So the idea is to use the tachyon prototype as a lure to catch the anti-Flash.
Caitlin asks Iris about the Burning Man Iris had blogged about and then seeks out Cisco, telling him that Ronnie is alive and a meta-human. The man in the yellow suit is constantly vibrating and seems faster than the Flash. Cisco also realises something about the night that Barry’s mother died, and it seems that one of Dr. Wells’ secrets is revealed in the post-logo scene – and it looks like a big one.